Multi-instance &#34;shadow&#34; system and method for automated resource redundancy reduction across dynamic language applications utilizing application of dynamically generated templates

ABSTRACT

A system and method are provided that allows, by adding a loadable module to the language runtime engine and overriding some of the core engine&#39;s operating system access functionality, the system to create a customizable copy of the installed application without creating complete copies of the actual files (scripts, executables, binaries, etc.) and without redundancies in content storage.

PRIORITY CLAIMS/RELATED APPLICATIONS

This patent application is a continuation in part and claims priorityunder 35 USC 120 to U.S. patent application Ser. No. 12/100,322, filedon Apr. 9, 2008 and entitled “Data Center Edition” which in turn claimspriority under 35 USC 119(e) to U.S. Provisional Patent Application Ser.Nos. 60/922,606 filed on Apr. 9, 2007 and 60/977,521, filed on Oct. 4,2007, all of which are incorporated herein by reference.

FIELD

The system and method relate generally to a generalized system andmethod for enabling execution of numerous altered versions of a computersoftware application on the common computer hardware/softwareinfrastructure, allowing significant reduction in the requiredexecution, memory and disc resources when these applications sharesignificant amount of the code. The solution can be generally applied toany type of computer infrastructure configuration, including, but notlimited to independent systems, grid and cluster-enabled systems,infrastructure-as-a-service systems, and generalized cloudarchitectures. The solution is applicable to both centralized andnon-centralized file management systems.

BACKGROUND

Software applications rely on the file systems management component ofthe operating system to provide access to the executable code of theapplication. Typically the generalized operating system's controls areused to manage the actual functions performed on the files comprisingthis codebase. While these generalized controls are sufficient for mostuses required by the file management clients, there is a significant gapin managing executable files for the highly scalable, multi-instancesoftware systems used in the modern web-enabled technologies, especiallythose utilizing dynamic languages.

Highly scalable multi-instance dynamic language applications createspecific demands on the file system and the operating system as a whole.The scalability requirement often dictated that the applications spanhundreds to thousands of physical or virtual hosts, each with its owncopy of the operating system, to achieve the capacity demands.Multi-instance form of deployment requires that a number of copies ofthe code, possible with a range of alterations, be executed in parallelacross the previously described cluster of nodes. Finally, the dynamicnature of the language and the application presents a challenge that thecode is read, executed (and even potentially modified and written backto the file system by the application) on every invocation. Due to theserequirements the default function of the file system presents clearchallenges in sharing, redundancy, speed of execution and the amount ofstorage required for efficiently servicing this type of application.

One of the popular models of delivering modern computer software is aCloud-base, infrastructure. Cloud infrastructure is generally mapped tothree layers: infrastructure components (servers, virtual machines,operating systems, etc.), platform components (data access queues,databases, file stores, etc.) and software (applications). Cloudsoftware delivery component (also knows as SaaS or Software as aService) presents an application that runs utilizing the network,hardware and systems software of the provider of the service and theuser accesses it via the network (most typically over http(s) protocol).This frequently employs many users of the same software, implementingthe same service, using the same provider.

In order to achieve the desired scale the software can be then deployedin either a multi-tenant configuration (all users share the sameapplication) or multi-instance configuration (customers are mappedlogically to a specific version of the application based on an arbitrarycondition such as company affiliation and many instances of a givenapplication are deployed). The multi-instance deployment allows theprovider to enable customers with higher level of control, flexibilityand customizability with respect to their application. In order toensure the latter some clients will require extensive customization oftheir service software, to the point where the same installation of theapplication is unable to serve the needs of all customers, and differentmodifications of the application, including code modified according tothe user preferences, is necessary.

Similar needs arise when logical isolation of systems is required inorder to comply with a variety of security modes in a virtualizedenvironments or when the software has self-generation capabilities,which modifies codebase dynamically throughout the execution process.

Traditional way of addressing these issues involved deploying multipleversions of software—each with its own codebase, execution stack andfrequently execution process. This method satisfied the basicrequirements for code customization and logical code segregation,however it created resource overhead in hardware, processing, labor andcosts. Thus in order to save costs, it is a frequent scenario that theprovider is running the software for multiple clients on a shared set ofhardware, thus reducing the hardware costs. However, when the copies ofthe software are differentiated as described above, each of them has tobe treated as separate piece of software, and has to be allocated diskspace, memory space, etc. for its function. This creates high marginalcosts for adding a new user to the system and leads to suboptimalutilization of the hardware resources.

Thus, it is desirable to allow the provider to run multiple instances ofthe computer software that share significant portions of the softwaremetadata and code via the multi-instance share-what-is-possible system.By using this system, SaaS providers can significantly reduce theirmarginal cost of creating a copy of the software for each additionaluser, while still allowing to customize it independently from othercopies according to user requirements.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a diagram illustrating an implementation of a businesssoftware application system, implementing a customer relationshipmanagement system, that incorporates various features;

FIG. 1B illustrates more details of the business software applicationsystem that incorporates various features;

FIG. 2 is a diagram illustrating an example of the user interface of thesystem in FIGS. 1A and 1B;

FIGS. 3A and 3B are a logical view and a physical view, respectively, ofa typical cloud architecture;

FIG. 4 illustrates an implementation of a shadow stream system;

FIG. 5 illustrates an implementation of a directory structure utilizingtemplate architecture that is part of the shadow stream system; and

FIG. 6 illustrates a management console of the shadow stream system.

DETAILED DESCRIPTION OF ONE OR MORE EMBODIMENTS

The system and method are particularly applicable to an customerrelationship management software system and it is in this context thatthe system and method will be described. It will be appreciated,however, that the algorithms, data structures, processes and modules ofthe system and method have greater utility since these modules,algorithms, data structures and processes disclosed herein can beequally applied to other CRM systems, as well as other business softwareapplication systems as well as other database software systems. Forpurposes of illustration, the described system is an implementation in acustomer relationship management (CRM) and groupware system. In theexample below, the CRM and groupware system described below is the SugarEnterprise version 6 that is soon to be commercially available fromSugarCRM Inc. In addition to the example below, the system and methodmay be more generally applied to any type of computer infrastructureconfiguration, including, but not limited to independent systems, gridand cluster-enabled systems, infrastructure-as-a-service systems, andgeneralized cloud architectures and the solution is applicable to bothcentralized and non-centralized file management systems.

The system may be implemented using a base class known as SugarBean, anda data retrieval API. A few of the methods provided in the base classinclude methods for building list queries, saving, and retrievingindividual items. Each specific type of data creates a subclass of thisbase class. The base class is called SugarBean in the illustrativeexample that is described below. There is at least one subclass ofSugarBean for each module. SugarBeans also are used for creatingdatabase tables, cleaning out database tables, loading records, loadinglists, saving records, and maintaining relationships. One example of aSugarBean subclass is a Contact subclass. The Contact subclass is asimple object that fills in some member variables on the SugarBean andleverages SugarBean for much of its logic and functionality. Forexample, the security associated with the Contact subclass isautomatically created for Contact by SugarBean that contains, amongother things, the functions and processes that are shared by the othermodules. Another example of a SugarBean subclass is Users which is amodule that is security related and contains the list of users as wellas users who should not have row level security (described below in moredetail) applied to them. For this reason these modules have the bypassflag set to skip adding the right join for verifying security. TheSugarCRM Sugar Professional system is a web based system with manyconcurrent users. Since this program contains critical data to theusers, it is imperative that they have quick access to the system andtheir data. The most frequent activity in the program is to look atexisting data.

FIG. 1A is a diagram illustrating a customer relationship management(CRM) system 100 that is an example of a software-based businesssoftware application. In one embodiment, the system 100 may beimplemented as a software system and the elements shown in FIGS. 1A and1B are thus implemented as a plurality of lines of computer code thatmay be executed by a processor of a computer system, such as a servercomputer wherein the various lines of computer code are stored in amemory associated with the computer system and the system interfaceswith a database 110 that stores the data associated with the system 100.The system may have one or more clients 102, such as a browserapplication executed on a typical computing device (a browser clientsession), that accesses the system over a communications network 103such as the Internet, a cellular network, a wireless network and thelike. The computing devices may include a laptop, table or desktopcomputer system, a PDA, a mobile phone, a portable wireless email deviceand the like. The client's 102 interactions with the system are managedand go through a set of one or more controllers 104. The controllers 104are the entry-point into the system for an entity that is using thesystem wherein the entity may be a person who accesses the system, suchas by using a browser application, a computing device or a softwareprogram that uses this entry point. The controllers 104 take care offunctions and operations including, for example, session tracking,session security and user authentication. The controllers also, for eachuser, prepare the screen/user interface or the wrapper for the contentand determine which module of the application the user is trying toaccess and get the requested module to process the request.

The system has one or more modules 106 that are components ofapplication functionality and provide certain functionality to theentity accessing the system. The modules 106 of the exemplary CRM systemshown in FIG. 1A may include, by way of example, a portal module, acalendar module, an activities module, a contacts module, an accountsmodule, a leads module, an opportunities module, a quotes module, aproducts module, a cases module, a bug tracker module, a documentsmodule, an emails module, a campaigns module, a project module, an RSSmodule, a forecasts module, a reports module and a dashboard module. Thesystem may include different, more or fewer modules and the systems withthose other combination of modules are within the scope of the systemand method. Each of these modules provides a different functionality tothe users of the system so that, for example, the calendar moduleprovides a calendaring functionality to the CRM system that isinstantiated with the system. The system may also include anadministration module that handles the typical administrative functionsof the system. In the exemplary system shown in FIG. 1A, each modulecontains a subclass of a SugarBean base object 108 and each modulereferences the SugarBean to retrieve the data from the database 110required for display and uses certain functions and operationsinstantiated in the SugarBean base object.

FIG. 2 is a diagram illustrating an example of the user interface 120 ofthe system in FIGS. 1A and 1B. The user interface may include a home tab121 (that is selected in FIG. 2) that provides a general overview ofCases, Opportunities, Appointments, Leads, Tasks, Calendar, TeamNotices, and Pipeline for the particular user since each user interfaceis customized for each user based on the access levels and parametersassociated with that particular user. The home tab may also includeshortcuts to enter various different types of data, and a quick form fornew contacts. The home tab also provides a quick overview of whatcustomer tasks and activities that the user needs to focus on today. Theportal module (selected using a “My portal” tab 122), contains a seriesof shortcuts which can link to any web site chosen by the user that mayinclude e-mail, forums, or any other web-based application, allowing thesystem to become a single user interface for multiple applications. Thecalendar module may be selected by a calendar tab 124 and allows theuser to view scheduled activities (by day, week, month or year), such asmeetings, tasks, and calls. The system also allows the user to sharehis/her calendar with coworkers which is a powerful tool forcoordinating the daily activities. The activities module is selectedusing an activities tab 126 and allows the user to create or updatescheduled activities, or to search for existing activities. By managingActivities within the context of an Account, Contact, Lead, Opportunity,or Case, the system allows the user to manage the myriad of calls,meetings, notes, emails and tasks that the user needs to track in orderto get the job done. The tasks are for tracking any action that needs tobe managed to completion by a due date, the notes allow the user tocapture note information as well as upload file attachments, the callsallow the user to track phone calls with leads and customers, meetingsare like calls, but also allow the user to track the location of themeeting and emails allow the user to archive sent or received emailmessages and to send or receive email messages.

The contacts module is accessed by a contacts tab 128 and allows theuser to view a paginated contact list, or search for a contact. The usercan click on a specific contact to zoom in on the detailed contactrecord and, from a specific contact record, the user may link to therelated account, or leads, opportunities, cases, or direct reports(related contacts). Within the system, contacts are the people with whomthe organization does business. As with accounts, the system allows theuser to track a variety of contact information such as title, emailaddress, and other data. Contacts are usually linked to an Account,although this is not required. The accounts module may be accessed usingan accounts tab 130 and the user may view a paginated account list, orsearch for an account. The user can click on a specific account to zoomin on the detailed account record and, from a specific account record,the user may link to related contacts, activities, leads, opportunities,cases, or member organizations. Accounts are the companies with whichthe organization does business and the system allows the user to track avariety of information about an account including website, main address,number of employees and other data. Business subsidiaries can be linkedto parent businesses in order to show relationships between accounts.

The leads module may be accessed by a leads tab 132 that permits theuser to view a paginated list of leads, or search for a specific lead.The user can click on an individual lead to zoom in on the leadinformation record and, from that detailed lead record, the user canlink to all related activities, and see the activity history for thelead. Leads are the people or companies with whom the organization mightdo business in the future. Designed to track that first point ofinteraction with a potential customer, leads are usually the hand offbetween the marketing department and the sales department. Not to beconfused with a contact or account, leads can often contain incompleteor inaccurate information whereas contacts and accounts stored in SugarEnterprise are core to many business processes that require accuratedata. Leads are typically fed into the Sugar Enterprise stemautomatically from your website, trade show lists or other methods.However, the user can also directly enter leads into Sugar Enterprisemanually.

The opportunities module is accessed by an opportunities tab 134 andpermits the user to view a paginated list of opportunities, or searchfor a specific opportunity. The user can click on an individualopportunity to zoom in on the opportunity information record and, fromthat detailed opportunity record, the user can link to all relatedactivities, see the activity history for the opportunity, and link torelated leads and contacts. Opportunities track the process of selling agood or service to a potential customer. Once a selling process hascommenced with a lead, a lead should be converted into a contact andpossibly also an account for example among other items. Opportunitieshelp the user manage the selling process by tracking attributes such assales stages, probability of close, deal amount and other information.The quotes module may be accessed by a quotes tab 136 and permits theuser to view a paginated list of customer quotes, or search for aspecific quote. The user can click on an individual quote to zoom in onthe detailed quote information. A quote is formed by referencing productand pricing from a catalog of products you may create. A presentationquality Portable Document Format (PDF) representation of the quote maybe created to fax or email to a client. Quotes may be associated with,for example, Accounts, Contacts, or Opportunities among other modules inthe system and the system is not limited to a quote being associatedwith any particular set of modules.

The products module may be accessed by a products tab 138 and permitsthe user to view a paginated list of products, or search for a specificproduct. The user can click on an individual product to zoom in on thedetailed product information. A product is used when assembling acustomer quote. The cases module may be accessed using a cases tab 140and may permit the user to view a paginated list of cases, or search fora specific case. The user can click on an individual case to zoom in onthe case information record and, from that detailed case record, theuser can link to all related activities, see the activity history forthe case, and link to related contacts. The cases are the handoffbetween the sales department and the customer support department andhelp customer support representatives manage support problems orinquiries to completion by tracking information for each case such asits status and priority, the user assigned, as well as a full trail ofall related open and completed activities. A dashboard module may beaccessed using a dashboard tab 142 and permits the user to view adashboard of the information in the CRM system.

The documents module may show the user a list of documents that the usercan access, view and/or download. The user can also upload documents,assign publish and expiration dates, and specify which users can accessthem. The email module allows the user to write and send emails and tocreate Email Templates that can be used with email-based marketingcampaigns. The user can also read, compose, save drafts, send andarchive emails. The campaigns module helps the user implement and trackmarketing campaigns wherein the campaigns may be telemarketing, webbanner, web tracker, mail or email based. For each Campaign, the usercan create the Prospects list from the Contacts or Leads or outside filesources. The projects module helps the user manage tasks related tospecific projects. Tasks can be assigned to different users and assignedestimated hours of effort and, as tasks are in progress and completed,users can update the information for each task. The RSS module permitsthe user to view the latest headlines provided by your favorite ReallySimple Syndication (RSS) feeds. These feeds provide news or other webcontent that is distributed or syndicated by web sites which publishtheir content in this manner. The system has information on hundreds ofRSS feeds available as supplied, and others may easily be added.

The forecasts module shows the user his/her committed forecast historyand current opportunities. For managers, the user can view your team'srolled up forecasts. The reports module shows the user a list of savedcustom reports not yet published, as well as a list of PublishedReports. Saved reports may be viewed, deleted or published, andpublished reports may be viewed, deleted or un-published. Clicking onthe name of a report zooms to the detailed definition of the reportcriteria (fields to be displayed, and filter settings) for that report,permitting the user to alter the criteria, and re-submit the reportquery. Finally, the dashboard module displays a graphical dashboard ofthe user's Opportunity Pipeline by Sales Stage, Opportunities by LeadSource by Outcome, Pipeline by Month by Outcome, and Opportunities byLead Source. The system also supports users putting graphs from theirreports directly on their dashboards.

Returning to FIG. 1A, the system also includes the database 110 thatcontains the data of the system and a security module 112 (row levelsecurity) that implements the security methods to control access to thedata in the database 110 since the database is shared by all users ofthe system and the data must be segregated based on the users and theiraccess level to different pieces of data. The system may also include adatabase abstraction layer 114 that is coupled between the database 110and the SugarBean object 108 and acts as an interface between thedatabase 110 and the SugarBean object 108. The SugarBean object 108provides the base logic required for retrieving, making available andwriting information to/from the database and each module createssubclasses of SugarBean (an example of which was described above) toprovide module specific details, module specific data and modulespecific data views. During the process of retrieving data from thedatabase, the SugarBean 108 makes calls that populate the row levelsecurity information into the SQL engine/database management system thatretrieves the data.

Once the data is retrieved from the database by the SugarBean object108, the module uses a template mechanism 118 and a theme 116 to producethe requested presentation (user interface) for the user. The templatemechanism reformats the data from the database 110 into a particularform while the theme adjusts the user interface according to the user'spreferences.

If, for instance, the user requests an HTML presentation of the detailview of the contact module for a specified contact, the system mayperform that request as will now be described. The request of the useris directed to controller named index.php that handles most of the logicfor the main application. The controller loads the current userinformation, verifies authentication and session information for theparticular user session, loads the language for the user (based on theuser preferences) and generates some of the user interface shell. Thecontroller then calls the contact module and request the detail view forthe specified contact. The contact module then retrieves the requestedcontact using the Sugarbean. The SugarBean verifies row level securityfor the requested contact at this point (with assistance from thesecurity module 112. If the record is not retrieved successfully, thenthe process aborts and the user is not allowed to view the data for therecord. If the retrieve process succeeds with the requested contactdata, the Contact module uses the templating mechanism, such as forexample XTemplate or Smarty, in the template mechanism 118 and the codefor the current user's theme (retrieved by the theme module 116) is usedto create the user interface for the presentation of the particularContact data to the particular user. The resulting user interface thenis sent back to the computing device with of client that requested it.

FIG. 1B illustrates more details of the customer relationship managementsystem 100. Like elements shown in FIGS. 1A and 1B have like referencenumerals. The system may interface with a typical browser application103 (being executed by a computing device) that can access the system100 over the web. For example, the examples of the user interface beloware web-based views generated by the system and displayed on a browserapplication. The system may further comprise an application programminginterface (APIs) portion 105, that may preferably use the well knownsimple object access protocol (SOAP), to interface with other existingsystem and applications. For example, the APIs may be used to interfaceto an email plug-in 109, such as an SugarCRM Plug-In for MicrosoftOutlook®, that enhances the email program to allow it to interact withthe system 100. As shown, the system 100, in one implementation, isimplemented on a web server application 107 (that may be the well knownApache web server that includes IIS functionality) that generatesdynamic web pages (using the known PHP language). The web server and theother elements of the system may be implemented as software running onone or more servers wherein the servers may use various differentoperating system as shown in FIG. 1B. The system 100 may also have anemail module 111 capable of sending email via a local program (that maypreferably be sendmail) or an email server leveraging the SMTP protocol.Now, a system and method that allow a provider to run multiple instancesof the computer software that share significant portions of the softwaremetadata and code via the multi-instance share-what-is-possible systemare described in more detail.

In one implementation explained below, the system and method relate tothe software applications implemented in the PHP programming languageand are executed by an HTTP server in order to deliver web pages as apart of the web application. The system and method can also be used toapply the techniques and systems described below for other programminglanguages and other servers.

The PHP language runtime performs file access by means of “streams” API,which act as an intermediary between the language functions and theoperating system. The API exposes basic file access function—such asopening file, reading, writing, getting information about file such asits existence, size, etc. The PHP language functions and operators, suchas include( ), fopen( ), fread( ), fwrite( ), stat( ) etc. use this APIto perform file operations. This API is commonly used to access externalresources—such as URLs, ZIP-archived files, etc.—in the same manner asregular files are accessed, and it can also be used to override accessto regular files by providing set of procedures to be called when PHPscript requires the file to be opened, read, written, etc. to beexecuted instead of regular operation system file functions.

The system includes the module that uses the API described above tointercept calls for files made by the PHP scripts and reroute callsaccessing multiple “virtual copies” of the file to address the singleactual file on disk. This way, the single file on the operating systemstorage can be used to represent an unlimited number of copies of thesame file in separate installs of the application, without incurringadditional costs in terms both storage space and caching mechanisms'memory and processing.

Since the streams API described above currently does not encompass allfile operations, such as changing file access permissions, access times,etc.—the system also overrides PHP functions dealing with suchoperations in order to direct these operations performed on “virtualcopy” of a file to the correct actual file on the operating systemstorage—either the master copy in the template or the instance copy ifone exists.

The system is unique in that it allows the files containing executablecode to be modifications to be applied to any part of the application onany of the deployed instances and have these changes be relevant only tothat specific copy, and have the copy immediately start using thechanged code, while still preserving zero overhead for all parts thatare still common. These common parts of the application are furtherreferenced as dynamically generated templates, or DGTs. In addition, noaugmentation to Operating System kernel is required with the designdescribed above providing highly portable, scalable, high-efficiencyarchitecture.

To better understand the system, the architecture of a typical cloudsystem 200 is briefly described with reference to FIGS. 3A and 3B. Asshown in FIG. 3A that is a logical view of the cloud architecture, thecloud architecture 200 has one or more software components 202, such asapplications, one or more infrastructure components 204, such as one ormore server clusters, one or more virtual machines and one or moreoperating systems, and one or more platform service components 206, suchas a services. As shown in FIG. 3B, the server cluster may include oneor more server computers (such as server 1, server 2, server 3, . . . ,server n) wherein each server computer has hardware (HW), an operatingsystem (OS), platform code and application code which means that thereis a significant amount of duplication of the portions in the typicalcloud architecture. Similarly, the platform service components 206 mayinclude platform software and platform APIs for each server computerwhich means that there is a significant amount of duplication of theservice portions in the typical cloud architecture. Now, the system thatreduces/eliminates the duplication of the typical cloud architecture isdescribed in more detail.

FIG. 4 illustrates an implementation of a shadow stream system 300 thatreduces the duplication of resources of the typical cloud system. Thesystem 300 has an operating system 302 and a language runtime engine 304that runs on top of the operating system. In one implementation, thelanguage runtime engine 304 may be a plurality of lines of computer codethat are executed by one or more processing units on a computer systemon which the language runtime engine 304 is instantiated. The languageruntime engine 304 may include one or more applications 306 (forexample, Application 1 306 a, Application 2 306 b and Application N 306n as shown in FIG. 4) that are connected to a shadow unit 308. Thelanguage runtime 304 may also include one or more stream connections 310(for example, Stream Connection 1 310 a, Stream Connection 2 310 b andStream Connection N 310n as shown in FIG. 4).

In one implementation, the language runtime engine 304 may include anexecutable module (a loadable module to a language runtime engine 304)that overrides the well known “stream” protocol used to typically handleoutside resources. In the example below, the streams handle files on thefile system (shown in FIG. 5) are described, but other extensions andstreams for other resources can be overridden by the executable module.The system can apply to any interpreted language runtime, such as Java,PHP, Ruby, Python, etc. The example described below assumes theapplication code is PHP code implemented as a set of PHP source files,as is customary for PHP applications, but the system can be used withother application languages and the like since it is not limited to thePHP example below.

The system designates two sets of application code files—“template” and“instance”. The template code (shown in FIG. 5) is the code that isshared between all the copies (i.e. instances) of the applicationvariant and the instance is the code specific to one specific copy ofthe application with a unique set of functional variation. The code ofeach application is assumed to reside in a separate directory on theserver's file system as shown in FIG. 5, as is customary for mostapplications.

When an HTTP request for the application is received by the Web Server,it is directed to the template code in the file system 312. Themanagement system described below determines, by examining the contentsof the request such as domain name, URL, parameters, etc., whichinstance this request is directed to and which template corresponds tothat instance, and establishes a link between the template and theinstance, for the duration of this request by the shadow unit 308.

When the language runtime engine 304 is required to open a source filein order to execute the source code contained in it, the shadow module308 intercepts this request and first checks if the file to be opened islocated inside the current instance and, if not, then checks if the fileto be opened is in the template. When the file is being opened only forreading or being accessed in order to check for it's existence or filesystem metadata (such as size, modification time, etc.), the system willoperate against the instance file, if it exists, and then fall back tothe template file otherwise. If the file is being opened for creation orupdate, then the instance file is always chosen.

For example, if there's a file called one.php on the template and nosuch file on the instance, and the application requests to open filenamed ‘one.php’ for reading and then reads it, the instance file isopened and the data contained in it is read. If then the applicationrequests opening the same file for writing, the file named ‘one.php’ onthe instance is created, and when the data is written to it, the file onthe instance gets the new data. Then, when the application requestsopening the same file again in the same instance, the new instance filewill be opened, thus returning the new data that had been writtenpreviously. However, if the same application running on another instancewould request ‘one.php’, it would still get the copy of ‘one.php’ fromthe template, thus reflecting the fact that one instance was customizedand another one was not. The process is completely transparent for theinstances, so each instance of the application can be implemented as ifit had exclusive own copies of all files, even though in fact only filesthat are customized on the instance are stored separately. -o The nameof the file chosen is then passed back to the language runtime engine304 for creation, reading, or update. If the file is not a part ofeither template or instance, the file name is passed directly to thelanguage runtime engine 304 without modification. Requests for deleting,renaming and changing a file's permissions are intercepted and modifiedas well, if necessary.

The process described above leads to creating “shadows” (virtualoverride copies) of the template files inside the instance, withouthaving to physically copy the files on the file system. This means thatneither the file system space nor the memory space (if such file iscached in memory) is used more than once even if multiple “shadows”exist. In this way, if the original file is actually physically updatedwithin the template, this change is instantly picked up by allinstances. On the other hand, if the file in changed in the instance,the “shadow” of this file for this instance is thereby overridden,allowing flexible customization of the application.

When the language runtime engine 304 opens a directory in order toenumerate files in it and that directory is inside the template or theinstance, the composite list of the files in both the template directoryand its corresponding instance directory is prepared and is returned asthe result. For example, if a directory called “custom” exists in boththe template and the instance, and in the template directory there arefiles ‘one.php’ and ‘two.php’, while in the instance there are files‘two.php’ and ‘three.php’, enumerating the directory on the instancewould return the list of three files—‘one.php’, ‘two.php’ and‘three.php’, and when ‘one.php’ will be accessed, it will be taken fromthe template, while ‘two.php’ and ‘three.php’ will be taken from theinstance.

If in the setup with certain template-instance pairs, certain files areaccessed more than once, the resolution for it is stored in memory andon the repeated accesses the file system is not checked but the storedcached result is returned in order to improve the performance.

The system allows for designating some parts of the application—such asparts for caching or storing the configuration—as “instance only”, inwhich case when the file from this part is required, the process aboveis modified so that the instance file is always used (or created atruntime), as if the template file did not exist.

The Management System Console

A management system (shown in FIG. 6) contains code, such as PHP code inthe example being described, that is added to the application (such as aCRM application), which allows for designating explicit relationshipsbetween requests (such as domains, URLs, etc.) and instances, so thatthe instance can be automatically configured on each request.

The system includes database storage (the file system 312 in FIG. 5),which the code of the management system refers to when the requestarrives, and if the request matches any of the records in the database,instance information from this record is used to establishtemplate-instance setup.

The management system also allows the operator to create new instances(as shown in FIG. 6) by entering new records into the database andcreating new instance setups, which initially contain only minimal setof files for maintaining the copy configuration, but can be furthercustomized by the operator on need.

For example, if the operator enters the description of the new site tothe database, which will be accessible at the URLhap://newclient.mymasshosting.com and the path for the storing theinstance is /var/www/newclient.mymasshosting.com/, once the URL isaccessed the first time, the system would automatically create thedirectory named above and copy or create the files specified in theconfiguration, such as initial database setup files containing the nameof the database server and the access details, so that on the firstaccess the copy of the application is automatically installed and readyfor work, without need for future operator actions.

After the application is thus prepared, it can be customized bydeploying modified copies of the files from the template into theinstance, or deploying additional files for the instance only,implementing additional functionality. For example, the SugarCRMapplication includes metadata files, which describe the representationof the data—such as customer contact data—on the system. If it isnecessary to modify this representation on certain instance—e.g. byadding or removing certain fields or rearranging them—new metadata filecan be deployed for the instance and will be immediately picked by thesystem and used instead of the template ones, while all the rest of thefiles will still be shared with the instance. Note that this is donewithout making any changes to the application itself—the applicationimplementation is done as if it had exclusive copies of all files.

Alternatively, if all the instances need to be modified—such as upgradedto a newer version or have certain additional functionality deployed byadding code files to the application, and that modification should beavailable to every instance, the modification can be made to thetemplate files, and will be immediately available to all the instanceswithout having to incur per-instance costs both in storage and upgradeefforts,

While the foregoing has been with reference to a particular embodimentof the invention, it will be appreciated by those skilled in the artthat changes in this embodiment may be made without departing from theprinciples and spirit of the disclosure, the scope of which is definedby the appended claims.

1. A generalized multi-instance computer application system for reducingthe marginal cost of deploying copies of a computer software applicationon the same computer hardware, comprising: a computer system having aprocessor; a store associated with the computer system that stores oneor more instances of an application and a piece of template code,wherein the template code is code that is shared between all of thecopies of the instances of the application; a language runtime engine,executed by the processor of the computer system, having a shadow modulethat overrides a file access of the computer system and, for executionof an instance of the application, uses the piece of template code. 2.The system in claim 1, where the template functions can be augmented ineach copy according to a customer's needs by extending the base templatevia metadata files and code files unique to the copy, while preservingthe same low cost of maintaining both the base template and only thefiles necessary to extend the specified functionality for the copy. 3.The system in claim 2, wherein the shadow module redirects a set of filesystem functions from the piece of template code to the code for theinstance of the application.
 4. (canceled)
 5. The system in claim 1,wherein the shadow module creates a new copy of a file for theapplication if the copy of the file does not previously exist in thestore.
 6. The system in claim 1, wherein a set of files is designated asbelonging only to the instances of the application.
 7. The system ofclaim 1, wherein the application is a customer relationship managementapplication.
 8. The system of claim 3, wherein the set of file systemfunctions is one of a file creation, a file modification, a fileremoval, changing metadata of a file, creating a file directory,browsing a file directory and deleting a file directory.
 9. A method, ona multi-instance computer application system, for reducing the marginalcost of deploying copies of a computer software application on the samecomputer hardware, the method comprising: storing, in a store associatedwith the computer system having a processing unit, one or more instancesof an application and a piece of template code, wherein the templatecode is code that is shared between all of the copies of the instancesof the application; overriding, by a language runtime engine executed bythe processor of the computer system, a file access of the computersystem; and executing, by the language runtime engine executed by theprocessor of the computer system when the file access is overridden, aninstance of the application, using a piece of template code.
 10. Themethod in claim 9, where the template functions can be augmented in eachcopy according to a customer's needs by extending the base template viametadata files and code files unique to the copy, while preserving thesame low cost of maintaining both the base template and only the filesnecessary to extend the specified functionality for the copy.
 11. Themethod in claim 10, wherein overriding a file access of the computersystem further comprises redirecting, by a language runtime engineexecuted by the processor of the computer system, a set of file systemfunctions from the piece of template code to the code for the instanceof the application.
 12. (canceled)
 13. The method in claim 9 furthercomprising creating, by a language runtime engine executed by theprocessor of the computer system, a new copy of a file for theapplication if the copy of the file does not previously exist in thestore.
 14. The method of claim 9, wherein the application is a customerrelationship management application running on the processor of thecomputer system.